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There are many substances out that cause damage to the brain and nervous system. Cannabis isn’t one of them. Similarly to lung damage, research keeps going back and forth in the cannabis and brain debate. Here, we’ve gone over arguments from both sides in hopes of answering an important question: does cannabis really kill brain cells? 

Does cannabis lower IQ or kill brain cells?

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There’s a lot of debate about whether or not IQ is an appropriate measure of intelligence and cognitive ability. However, cannabis critics often claim that the herb lowers IQ, and therefore causes brain damage. This fear stems from a New Zealand study published back in 2012.

The study looked at 1,037 individuals from age 13 to age 38. They found that cannabis consumers showed an 8 point drop in IQ by the age of 38. There are a few issues with this study, though. The number of people who showed this decline was quite small, only 38 people out of 1,037.

These same people also used significantly more herb than the average person. Specifically, these people were classified as having trouble with cannabis abuse.

Other criticisms of this study suggest that this study failed to rule out other factors that cause IQ decline. These include family life and whether or not they dropped out of school.

New research says cannabis not linked to low IQ

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Don’t freak out just yet, though. A couple of more recent studies counter this claim. Research published in December of 2015 compared the IQs of identical twins. In their twin pairings, they picked couples where one twin had either used or abstained from cannabis over the past 10 years.

After controlling for environmental factors, the research team found no measurable link between cannabis use and decreased IQ. Cannabis consuming twins did lose about four IQ points over time, but their non-using identical twins also experienced the same drop in IQ. So, it’s likely that something else, not the cannabis, caused these changes.

Lead study author Nicholas Jackson explains:

Our findings lead us to believe that this ‘something else’ is related to something about the shared environment of the twins, which would include home, school, and peers. – Jackson

The results of the twin study are supported by another piece published just a month earlier. British research led by Valarie Coran looked at the effects of teen cannabis use on IQ. The team found that teens who consumed less than 50 times did not differ from non-users in IQ or educational performance.

The adolescent use of tobacco, however, is associated with cognitive decline.

While these studies don’t suggest a drop in IQ in teens, this doesn’t mean it’s a good idea for youngsters to use cannabis recreationally. There’s a lot going on in a developing brain. Additional research has shown that earlier onset smokers experienced greater issues with impulsivity than older consumers.

The study authors suggest that cannabis is a herb worth waiting for. These results are not present in late-onset consumers.

Does cannabis cause brain abnormalities?

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One of the next big arguments from cannabis naysayers is that the herb causes brain abnormalities. One 2014 study suggested that regular cannabis use causes brain changes in areas responsible for emotion and motivation in young adults.

However, this study is also flawed. The researchers failed to answer the big chicken and egg question. Were the young adults using cannabis because of these brain changes, or did these changes develop after exposure to the herb?

This study again is countered by a more recently published article. In 2015, researchers found that daily cannabis use was not associated with brain changes in adolescents or adults. The research compared 29 adult daily users and 50 adolescent daily users to the same number of non-using controls.

The team controlled for previous alcohol use more tightly than other studies on brain morphology. They then used MRI scans to study the shape of the brain.

Can you guess what they found? No difference between users and non-users. Daily cannabis use did not cause significant changes to the structure of the brain.

A study from back in the 1970s also spread fear that cannabis causes brain damage after testing the herb on monkeys. However, this study turned out the be false and cruel. To test the effect of cannabis on monkey brains, they covered their snouts with a gas mask pumped full of cannabis smoke for five full minutes.

The monkeys did not have access to oxygen, and they died of suffocation. Severe oxygen deprivation causes brain damage.

Is cannabis good for the brain?

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Neurotoxins are compounds that damage brain and nervous cells. Aspartame and fluoride, for example, are two substances which can cause nerve cells to malfunction. Cannabis is not a neurotoxin. In fact, compounds in the herb can prevent damage from neurotoxins.

Cannabinoids, the active compounds in cannabis, are potent antioxidants. This means that they protect your DNA from damage caused by environmental and biological toxins. Research has shown that these antioxidant properties are neuroprotective, combatting damage to brain cells.

Two additional studies have found that cannabis protects against neurotoxins associated with Alzheimer’s and Parkinson’s Disease. A 2015 study found that non-psychoactive CBD reduced the presence of a neurotoxin known to trigger Parkinson’s.

Additional research found that psychoactive THC reduces the build-up of amyloid plaques and inflammation which lead to Alzheimer’s disease.

Further, compounds in cannabis are some of a handful of substances that promote the growth of new brain cells. This process is called neurogenesis. While scientists once thought the brain stopped developing in your early twenties, we know now that the adult brain is capable of making and growing new cells.

Cannabinoids aid in the growth and differentiation of these cells.

All of these facts suggest that cannabis may actually be beneficial to the brain, not harmful. Though adults and the elderly may reap more of these benefits than young people. In children, adolescents, and teens, the brain is still growing and has not yet reached the peak where age-related degeneration begins.

Yet, the herb is quite promising for the brain health of adults and seniors. Regardless, researchers have yet to make a clear link between negative cannabis-induced brain changes no matter how old you are.

Has cannabis helped or hurt your brain? Share your story with us on social media or in the comments. We’d love to hear from you!

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Delilah Butterfield

Delilah Butterfield is a Pacific Northwest native with a passion for cannabis and natural health. Contact her on Twitter @delilahbfield.
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